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Welcome to Corona Films
Corona Films Incorporated is a leading
manufacturer of capacitor grade mica paper.
A wide variety of controlled test procedures and
over 40 years of experience provide customers
with the best mica paper at the lowest possible
price. We specialize in thin sheets from
1/2 mils and any thickness between.
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About our Mica Paper Product!
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Mica is used in our capacitor paper because of
it's outstanding electrical and thermal
properties. Our mica paper starts out as
100 % muscovite mica. After cleaning, the
mica goes through a special manufacturing
process to insure proper flake size and pulp
consistency.
Widths: 1/2 inch up to 20 inches, all
rolls are slit to order
Shipping: Freight Collect
Returns: By approval of spindles and pads
To confirm phone orders, please fax copy of
Purchase Order
Phone:
978-597-6444
Fax: 978-597-5685
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Packing List |
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All information will be presented in a packing
list attached to the top box on a skid or the
last box on a loose shipment. The packing slip
will include code, weight/ square feet, caliper,
width, number of rolls per code, box number, and
accumulated gross weights in as large an
increment as possible under 100 lbs. |
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Weight |
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Split Spec. Max roll dia. 7.00 in.; Min. roll
dia. 4.375 in.; <.0062 width; 3 in. I.D. cores. |
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The weight samples are dried in an oven or on a
hot plate at above 100 degrees C, and weighed on
a balance accurate to .01 of a gram. The sheets
are labeled front, center, back. The sheets are
weighed hot as a group and divided by four for
the average. The individual sheets are weighed,
the values recorded, and the range calculated.
The average value is used on the quality
shipping report. The individual values and the
range are used for our in-house process control.
Weight is a far more accurate measure than
caliper. The variables are accurate cutting, the
balance, and drying, all controllable variables.
Most engineering specifications read and control
the average weight in grams / square feet,
quality control inspectors have taken a one inch
wide strip by 12 feet, weigh it, and say this is
the average weight. not so, our values are based
on the master roll and the individual 6 inch x
24 inch sheets. If an individual sheet falls
outside of a specification that part of the web
or the roll is rejected internally. This same
reasoning is applied to caliper, however, here
we have the standard deviation to estimate the
population and the sheet compliance to
specification. It is very possible to have a
dramatic (.05 mil) change in caliper from one
inch to another. this is the result of stacking
the deviation 10 times. This is not likely to
occur in the actual caliper where four to six
rolls across the web are stacked. |
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Based on the average of (3) six by twenty four
inch samples. These are sampled every six inches
across the machine. |
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CAT. # |
MIN. WT. |
AV. WT. |
MAX. WT. |
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GR/SQ FOOT |
GR/SQ FOOT |
GR/SQ FOOT |
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CF 50 |
1.75 |
2.000 |
2.25 |
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CF 60 |
2.06 |
2.305 |
2.55 |
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CF 70 |
2.38 |
2.715 |
3.05 |
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CF 80 |
2.73 |
3.015 |
3.30 |
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CF 90 |
3.08 |
3.440 |
3.80 |
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CF 120 |
4.13 |
4.640 |
5.15 |
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CF 130 |
4.55 |
5.050 |
5.55 |
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CF 140 |
4.90 |
5.300 |
5.70 |
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CF 150 |
5.25 |
5.750 |
6.25 |
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CF 185 |
6.48 |
6.990 |
7.50 |
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CF 200 |
7.00 |
7.600 |
8.20 |
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CF 300 |
9.75 |
10.750 |
11.75 |
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Tests are based on breaking down 16 two layer
test caps at 500 volts/ sec. Rise. The caps are
wound on a 1.375 dia. Mandrel. The foil is 1.75
inches by app. 72 inches. The corona film is 2.5
inches wide. |
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CAT. # |
TEN. |
E.B. |
AV. -KS E.B. |
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LB/IN WIDTH |
D.C. V/MIL |
D.C. VOLTS |
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CF 50 |
1 |
>1250 |
1350 |
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CF 60 |
1 |
>1800 |
2050 |
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CF 70 |
2 |
>2250 |
3060 |
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CF 80 |
2 |
>2500 |
3700 |
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CF 90 |
3 |
>2500 |
4400 |
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CF 120 |
3.5 |
>2500 |
5900 |
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CF 130 |
4 |
>2500 |
6500 |
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CF 140 |
4 |
>2500 |
7000 |
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CF 150 |
4 |
>2500 |
7500 |
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CF 185 |
5 |
>2500 |
9250 |
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CF 200 |
5 |
>2500 |
10000 |
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CF 300 |
5 |
>2500 |
10000 |
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Caliper |
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The caliper is measured as per ASTM D-374 method
C with added techniques. Ten layers are used in
all cases. The measurement obtained is a result
of the weight of MICA, the surface finish of the
sheet, the relative humidity, the acceleration
of the drop, the settling time of the anvil, the
temperature, plus unknown variables. For quick
results, it is best to dry the sheets above 60
degrees C before conditioning at 23 degrees
centigrade and 50% RH; this lets the MICA paper
come back to the test humidity level rather that
dry down to it. Storing the rolls at measuring
conditions for 24 to 48 hours prior to testing
is an excellent technique. Our procedure is to
settle the micrometer on the sheet, lift it off
(.3 of a mil) until the sheet can be pulled to
the test mark and dropped ( not let down-
dropped). The operation is repeated across the
sheet; the average calculation and the standard
deviation are calculated and recorded with N,
the number of readings. The value shown on our
quality shipping report is the closest or the
same as the outside of the slit roll. Off
machine slitting if a 25 lb. master roll the
values would be those at the start of the roll.
For a 50 lb. master roll the first cut of the
slit roll would end at the center of the master
roll the second cut would end at the end of that
roll. This would be the value on your shipping
quality report. |
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Average
Caliper |
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Based on test at one inch intervals across each
master roll. |
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CAT. # |
CAL. MIL |
TOL. MILS |
ST. DEV. |
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AV. |
PLUS MINUS |
MAX. |
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CF 50 |
0.54 |
0.04 |
0.025 |
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CF 60 |
0.61 |
0.04 |
0.025 |
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CF 70 |
0.68 |
0.04 |
0.025 |
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CF 80 |
0.78 |
0.04 |
0.030 |
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CF 90 |
0.88 |
0.04 |
0.030 |
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CF 120 |
1.18 |
0.05 |
0.030 |
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CF 130 |
1.30 |
0.05 |
0.030 |
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CF 140 |
1.40 |
0.05 |
0.030 |
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CF 150 |
1.50 |
0.06 |
0.030 |
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CF 185 |
1.85 |
0.10 |
0.035 |
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CF 200 |
2.00 |
0.10 |
0.035 |
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CF 300 |
2.85 |
0.20 |
0.070 |
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